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What is this cutout in the Spitfire cockpit glass?

This is a still from the film Dunkirk. I realise this is not a historical document, but I have also found a similar feature in photos of real Spitfires. What is the purpose of this?

Its for use at a drive-through window?

Could it have been intended for a star navigation instrument?

Another thought occurred to me, Further in the comments there is mention of early models having complicated canopy release systems, perhaps this was a knock out to allow for Very pistol signalling in case trapped in a downed plane.

Back in the day (1970s) I was told that DV panels were to facilitate photography.  Whether Spitfires were intended to be used for reconnaissance I don’t know.

What?
According to flight manuals, it's the direct vision panel. The panel would have been punched out to make an opening and maintain a view on the outside in case the windscreen had been obscured for some reason.
Seen on either side, depending on the model
Some Spitfire models had it on the left hand side and this reproduction of the manual for model II actually mentions it on the port side:

Source

Spitfire I: On the left side, source
It seems the side changed later, the official manual locates the panel on the right side for models V (5): VA, VB and VC.

RAF Spitfire Pilot's notes - Air publication 1565 from UK Air Ministry. Source www.airwar.ru (pdf link)

Purpose
The manuals are only vague about the reason the windscreen can be obscured, still a reason often cited the rapid altitude gain allowed by the aircraft creating condensation in the cockpit:

Note the punch-out panel on the canopy cover, an early solution to the new problem of canopy misting caused by the rapid altitude changes possible in the Spitfire.

Source: Flight Journal (pg 28)
Fogged windscreen is a plausible, as are a few other, cracked windscreen, oil spilled... we'll never know, online comments suggest it was never used.

Seen this description elsewhere too supposedly reported from official documents, so it may well be right, but really it seems to be in entirely the wrong spot for that. In fact, the fact that it is in the pilots line of sight in general seems like a strange design decision. Also seen it reported as helping relieve pressure to facilitate bail-out at high speeds too...

Cool. I suppose the pilot would side slip the plane, and lean to his left and look through this tiny window, to land with a wind screen obscured by oil or mist or something else.

There are only theories? Wouldn't the manufacturer know for certain why they're adding a small window to the canopy?  I agree these sound like good reasons, but just curious why you say "theory" and not, say, "reason".

Could the pilot reach through there with a window cleaning tool?  Would that dictate which side it was on so he could control the aircraft with dominant hand rather than use that for cleaning window?

It appears some models may have had them on the right

Mins is right, but it's a more general thing: Glider planes have them too, or at least those built in the 80s that I flew in the 90s.
One of their effects is that they whistle in the (self-made) wind. Basically any deceleration is immediately noticeable in the note of the whistle going down (helps avoid stalling)... Relevant for a glider, but probably inaudible over a Spitfire's noise!

I've seen such windows on all gliders I've ever seen or flied in, but they could all be closed with a sliding part.

I recall ventilation being poor in small planes, not familiar with gliders except they might have no fans to cool you when waiting to taxi, could this be for fresh air when there is a lot of sun coming through a large clear canopy?

@KalleMP -- yes this is definitely part of the reason for the existence of this feature on many gliders

In addition to heat, it's also to be able to talk to the person hooking you up to your tow.

The ORIGINAL Spitfire I Pilot's Notes (as opposed to the concocted and suspect "1940 Spitfire Manual", whatever THAT means, quoted above) clearly state that the panel is for "Emergency use" and on the PORT side. "Port" is bolded in the text. The real para number is 45 in the Spitfire I and 37 in the Spitfire II Notes.
The panel allows airflow which may (or may not) clear the fogging of the front panel/hood and also could provide some perspective on landing to maintain the "triangle" of the runway edge and nose, should the hood be jammed. It also releases pressure aiding in getting the hood open in an emergency, necessary for vision or for bailing out...these early hood not having the Martin Baker quick release system.
The knock out panel was always on port (the photo above actually shows this but because of the thickness of both layers of glass, only the studs can be seen. If it were in fact on the starboard side, the outline of the panel could be seen.
The knockout was dispensed with from Mk V onwards. Some later manufacture Spitfire I's also lacked it, I believe, after the MB gear was introduced but have not been able to definitively confirm that.

The knock out panel was most likely meant to be broken with the pilot's elbow to equalize pressures, in order to allow the canopy to slide back for bailing out, as the suction of the air due to its shape was preventing it moving at high speeds. If the canopy could be slid back in flight in the first place, there would be no need for a knock out panel to clear condensation or oil or to look outside.

Please add further details to expand on your answer, such as working code or documentation citations.


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What's an estimate for the cost of the cockpit technology on a 747 or 777?
Can anyone share what the percentage cost or dollar costs of cockpit instruments and related software is within a 747 or 777?
PS-  I'm a physician working in medical safety.  Physicians can no longer memorize it all (haven't been able to for decades- but now admitting it with more frequency).  They need instruments as in a medical cockpit.  Currently hospitals spend hundreds of millions on electronic medical records, but do not heavily invest in software to aide diagnostic and therapeutic decisions.  I am trying to develop a comparison between professions that deal with complex systems and the type of investments in software and guidance systems to handle complexity.  Thanks for any help!

Clarification: IBM Watson "reads" all emerging oncology therapies and uses AI to match patients to appropriate therapies at Mayo and other organizations.

Thanks for your thinking on this analogy.  Help me drill deeper.  If the electronic record only records what the doctor does, but does not guide clinical thinking, is it more like the black box?  What i am trying to get at is the lack of investment in intelligent guidance systems.  Yes Watson would be an example of supporting thinking.  But it is not a comprehensive solution to the central questions that come up as you see the patient.  What is the diagnosis, best, safest tests and therapy for each unique situation?  The EHR does not come with this embedded.

A lot of the cost of the avionics are for reliability consequences: making the computers rugged and able to withstand turbulence and hard landings, making them redundant so that there are no single points of catastrophic failure etc. The avionics of modern civil airliners are used in Level D simulators as well. For the simulators, flightworthy computers are not necessary and the software is usually rehosted onto standard PCs.
A package of avionics, input devices, rehosted software plus licenses would make up 10 - 15% of the sales price of a Level D device, which depending on the type is between 10 - 20 million USD - so all in all between 1 and 3 million USD.
On the other end of the scale, a full suite of modern avionics for smaller GA airplanes such as Garmin G500 can be obtained for USD 20,000. Its bigger brother the Garmin G1000 is on board of the Cessna Citation Mustang. These systems have a significant portion of the functionality of the big airliners, for 10% of the price.
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Is it legal for a crop duster to fly right over my house while spraying?
A crop duster is flying directly over my house while spraying. I can see the mist coming out while I am standing in the middle of my yard (6 acres). Is this legal?

related, if not duplicate: https://aviation.stackexchange.com/questions/39571/helicopter-crop-duster-minimum-altitude-over-homes-not-field https://aviation.stackexchange.com/questions/39448/can-i-stop-crop-dusters-repeatedly-flying-over-my-home

Is the pilot ACTUALLY SPRAYING CHEMICALS over your house or is he merely flying over your house while working a field?

People tend to radically over-estimate the angular elevation of an object in the sky. (You can easily verify this by looking up the angular elevation of a star or planet, or the sun or moon, or even the International Space Station, at your location at any given point in time on-line and asking someone else to observe and give their own estimate.) 30 degrees elevation is often perceived to be more like 45, 45 degrees is seen as more like 60, and 60 degrees is perceived to be straight overhead. You are lying flat on your back looking straight up and seeing the aircraft pass directly overhead?

Over your house, or over the middle of your 6 acre yard?  (Are they your crops?!)

No. 14 CFR 137.37 - Manner of dispensing is pretty clear:

No persons may dispense, or cause to be dispensed, from an aircraft, any material or substance in a manner that creates a hazard to persons or property on the surface.

Flying directly over you or your house while spraying is illegal. There are factors like altitude etc, but spraying pesticides over people is rarely legal.

How do we know the substance being dispersed creates a hazard to person or property?

@Jonathan Crop dusting usually means spraying pesticides. I've assumed that's what the OP means.

I think sometimes they spray fertilizer.

Aerial application can involve many various products, some harmful, some harmless. Some products are completely harmless ("glue" for rapeseed pods), and some merely do not pose a danger in a specific concentration with a specific distribution method. The suggestion that any and all aerial application near or over people is hazardous and illegal is misinformed and perpetuates popular myths that are harmful to the aviation industry.

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Which channels to listen to on liveatc concerning arriving flights?
For fun, I decided to watch arriving aircraft to airports on flightradar24.
Now, what I'd like to do also is simultaneously listen to ATC traffic concerning these incoming flights.
I've found Liveatc.net and, for example, there're plenty of choices of channels for JFK airport.
Which channel should i listen to if I'm interested in the radio exchanges concerning holding patterns and final descents? Is this handled from the tower?
(If JFK isn't a good example, feel free to recommend any other airport, European airports preferred. I tried LHR, FRA and CDG but it seems they aren't covered by liveatc.)
So, the more general question is: how are the channels labeled on liveatc that are about holding patterns and approaches?

Yes, tower is typically the last frequency they use until touchdown. You can also listen to the approach frequency which will handle sequencing and holds.

Possible duplicate of What ATC entities does a commercial airliner communicate with?

LHR wont be available as it is illegal to provide a stream of ATC in the UK

Same for Germany, it's illegal to listen to any non public radio telephony (like airband) as long as you are not involved.

See also: What is a TRACON? to have a better view of who do what in the US (terminology is different in Europe).

If you want arrivals the relevant feeds on live ATC are:

NY app (CAMRN)
NY app (ROBER)
NY app (FINAL)
KJFK Tower
KJFK Tower #2
KJFK Tower 119.1
KJFK Tower 123.9

CAMRN will receive approaches from the south and ROBER will receive approaches from the east. They will then pass planes to final to be lined up to the runways. Final will then pass planes to the appropriate tower frequencies, depending on which runway they are assigned. There are two separate tower frequencies of which there are two separate feeds. Items 4 and 5 are both frequencies combined (usually one in the left ear and one in the right) from the two different frequencies. The feeds are done by volunteers so there's no way to know their location. I haven't listened to KJFK so one feed might be better to hear planes from different directions. Feed #1 includes the TCA. I find it daunting to hear two feeds at once so I would recommend using either 6 or 7.
To be honest, unless there's something unusual going on, tower feeds are pretty boring. By the time they get to tower freq they are done maneuvering and are established on final. All tower does is clears them to land and and gives them exit instructions. If you are watching FR24 the approach feeds are more interesting.
Another interesting approach to watch, at least for me, is KMEM between about 2230 and 2330 Central time when all the FedEx flights are coming in to the hub. Gives you a good idea of the flow of ATC.
As Dave mentioned in comments, none of the UK airports will be on LiveATC for legal reasons.

Thanks! As said, it's the approaches i'm interested in. For information, for Europe, i figured out that Zurich (ZRH) and Amsterdam/Schiphol (AMS) are two examples of somewhat busier airports that are available on LiveATC.


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Logging Dual Received in a Single-Pilot Turbojet, FAA
Can you log dual received in a single-pilot turbojet on Part 91 flights if the PIC is type-rated, holds a valid MEI and instruction is being given?
Can the AMEL-rated student log AMEL category and class time if receiving flight instruction in this scenario without holding a type rating in the aircraft, or can only dual received be logged. In the latter case could you log the time at all if it cannot be tied to a category and class.
Similar scenarios that come to mind would be instruction for an initial type rating in the aircraft instead of a simulator. How is that time logged and what qualifications would that instructor and student need?
Any inputs with associated regulations or letters of interpretation are appreciated.

Re opening para: why would the fact that its a single-pilot aircraft be relevant?  So is the Cessna 172, but dual received is often logged in it--

Re: quiet flyer - If the aircraft is certified for single-pilot operation it does not require two crewmember for operations which affects how time can be logged in the aircraft. The question then is do you need a type-rating to log dual multi-turbine received?

Re: 757toga - A single-pilot jet that only requires one pilot.

Why would you NOT log dual received if you are receiving instruction?  Did I miss some subtlety?

Re: Michael Hall - Sure I can log dual received, but does this time count as FAA total time and can it be logged it as AMEL time? I was told I cannot because I am not type-rated in the aircraft, and that is why I am looking for clarification on this.

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How do aircraft differentiate between missile locks?
I have explored many similar questions such as:

How does a Missile Lock Work?
How is a missile lock detected?

In reading there respective answers, I have learnt about the multitude of detection mechanisms employed, but one question lingers and remains unanswered:

How would an aircraft differentiate between the multiple missile lock signals it would likely be receiving?

In a dogfight scenario (although they can occur over a large distance) a single aircraft may well detect the signals emitted by either the missile as part of an "Active Radar Homing" mechanism, or from the launcher itself as part of "Passive Radar Homing", regardless of whether the aircraft is the intended target, presumably causing every aircraft in the area to be notified to the single missile lock.
I don't pretend to be well versed on the subject of aerial warfare, yet I consider it nonsensical that every aircraft in the engagement be notified to the missile lock of a single aircraft as it would distract the pilots, all of whom would be required to ensure that they are not the targets.

Non-holographic radar systems such as those used in fighter aircraft and active guided missiles only point in one direction at a time. Normally, when the radar is in search mode, a mechanism inside the radar makes the beam move from side to side (possibly up and down as well), so it has a wider field of view and can pinpoint the direction of any aircraft it finds.
The aircraft with the radar warning receiver (RWR) sees a brief pulse of radiation every second or so: only when the beam is pointing in its direction. This way, it knows the radar emitter is in search mode, and the direction of the emitter. Every aircraft in the radar's field of view will see the beam at different times, and they will all see the radar on their RWR screens. In a combat zone this is potentially a lot of emitters, but the RWR can analyse the radar signal to identify the radar: what type of aircraft, SAM, or ground radar it is, and whether it's friendly or enemy.
Getting the position of the target only every second isn't good enough to guide a missile towards it. When the radar is in track or launch mode, it stops scanning the beam, and keeps it pointed at the target aircraft.
The RWR on the target aircraft now sees much faster pulses of radiation, so it knows that it is the sole target of the radar. At this time, it can warn the pilot of a missile lock. But because the radar is now only pointing in this one direction, other aircraft in the area don't get illuminated by radar at all. Their RWR systems won't pick anything up. Only the aircraft that's actually threatened gets the missile lock warning.
In addition, the same analysis that can identify what type of radar is illuminating the aircraft can also identify fully active radar-guided missiles. Like when the aircraft's radar is in track or launch mode, the missile's radar emitter only points in one direction, and doesn't scan, so only the target aircraft will see it.

Obviously it's a little bit more complicated than this. There are a lot of details about how frequent the radar pulses are, and how the RWR knows the range of the source, but I hope I've captured all the important information in an understandable way.

I'm a little tempted to suggest RWR should be described to a layman as "a warning indicating that someone out there wants to know way more about your position and velocity than you are generally comfortable with." =)

In short, the onboard Radar Warning System computer analyzes the data and determines whether the missile has locked onto the aircraft.
In general, aerial warfare is very complex and it is very difficult to explain in the real situations. Basically, the radars use different modes while engaging aircraft (from other aircraft or ground based SAM batteries):

First, the scan the area for any threats.
Once any threats are detected, they track the threats.
Once the threat is tracked, it is prioritized and the radar/missile locks onto the target.

Radars can change either the frequency or the strength between these modes. For tracking a target, the radar is basically scanning a smaller portion with higher intensity to get more resolution. So, the radar signals will be stronger.
Now, consider the dogfight scenario you mentioned; every radar in the area will be emitting electromagnetic radiation and get the returns from all the radars in the area. This is, to put it mildly, confusing. So the radars adjust the frequencies so that they have different values and track the aircraft.
Now, the RWR uses these two information to differentiate between the various radars. By looking at the frequencies/strength and comparing it with the available onboard library, it can determine which radar is emitting in which mode. In fact, creating this library is (one of) the most difficult things in design of ECM systems, which is the reason why everyone is trying to 'probe' other's defences.
This image shows a typical RWR display, where the threats and their locations are shown. The stronger the radar signal is, (probably) the closer is the radar source and more imminent is the threat.

Typical RWR display, from gizmodo.com
This display shows an F-15 at the 7-o'clock position and two surface-to-air missile (SAM) sites, an SA-5 "Gammon" and an SA-6 "Gainful", at the 12- to 1-o'clock position. The RWR computer has determined the SA-6 to be the highest priority threat in the area, enclosing it with a diamond.
There are other ways to determine of the missile is locked on the aircraft: you can use a doppler radar to track the missile and calculate the intended trajectory. However, this means exposing the aircraft to the radars in the first place.
Once the onboard computer analyzes the data and determines the the threat and severity, it alerts the pilot, usually by changing the display and in some cases, by audible alerts. In such cases, the pilot can release the countermeasures or the system can do so automatically.
However, the real situation will be much more complex with all the countermeasures, ECMs and ECCMs etc. But this should give a basic picture of the situation.

Most modern ones are TWS.


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PBY-5A exhaust modification?
What is the function of these “tubes” that cover the outboard exhaust stacks on some PBY-5A and PBY-6A aircraft?

German Wiki says the exhaust gases were used to de-ice the wings. Could it have something to do with that?

I'm going with a cabin heating system for northern operations.

Thanks for the suggestions in the comments.
Using the term “heat exchanger” I was able to find an Aircraft Modelling forum that gave the answer I was looking for.
Interpreting wartime photography: Catalina in Ceylon
It is indeed a heat exchanger system for leading edge anti-icing. The tail appears to have a separate anti-ice system that burns fuel for heat. This thermal anti-icing was introduced on late model PBY-5A. It probably was an optional system.

On some jets with heated LE, usually hard LE non-slatted ones, the LEs are heated above the boiling point, 220F or so, by high temp bleed.  They are "evaporative" systems that are like spitting on a steam iron, and the idea is to prevent runback ice forming behind the leading edges.  If you have slats, you can tolerate runback ice and the system can run much cooler, around 140-160F.

Apparently the German Wiki pointed in the right direction :-). It also says that the Catalina was the first plane to use such an exhaust operated heating for anti-icing ("In addition, their exhaust fumes served for the first time the deicing of the wing." (Google translated)).


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What are those things on the B747 engine pylons?
I noticed some dots and lines on the Boeing 747 engine pylons. What are they?

The above image is as seen in this video at 2:18.

The linear objects are the strut aft fairing panel latches. The panels hinge along the dark horizontal line seen in your photo. There is an engine support strut beneath the panels. There are also hydraulic system components contained in that compartment.

These are latches holding the engine support pylon panel in closed. Behind this panel is the diagonal brace.
This area was modified ~1992 due to the El Al Flight 1862 and China Airlines Flight 358 crashes.

See FAA Lessons Learned (via archive.is).

I agree with the previous writer on the latches for those panels on the engine struts. Regarding some of the other objects on the strut, I'd have to hazard a calculated guess, since I've been retired off of the airplane for 10 years.

the three circles are probably clear ports with glass or plastic lenses to inspect possible pressure gauges behind them without having to pull off the entire panel to read them. Most notably, they might be to read pressures of fire retardant bottles in case of an engine fire. Airline Customers might choose various configurations on things on their planes, but on our aircraft, there were two bottles per wing that could be used for engine fires.

There is also a thin black line above and to the left of those circles. This is possibly a fuse pin marker. If the aircraft is normal, the line would be continuous and straight. If one of the fuse pins is broken or damaged, the black line would not line up straight and would indicate something wrong with the fuse pin inside. Fuse pins were installed on the engine struts, and at a certain temperature or stress level, they would break, allowing the engine to depart the aircraft instead of burning up the wing. We checked those markings carefully to be sure they lined up normally on each preflight, indicating all was well inside the panel. I never saw one that was misaligned, which is good!


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What size/engine/payload aircraft would be needed for carrying two passengers and a motorcycle?
I'm not even in the realm of knowledge of aircraft so don't chew me out on lack of terminology please.
My objective is to fly myself and a 300-pound motorcycle to destinations to ride from there.
I weigh 185 lbs, the motorcycle weighs 300-400 lbs, any secondary seating and other interior furnishings would most likely be removed to reduce weight, and, obviously, all the necessary components would stay. As a side note, the aircraft needs sufficient enough door to get a small motorcycle in. Let's not even talk about how unsafe this might be; this is all hypothetical.
How large, or what class, of an aircraft would be needed for such a task to be completed?

A Cessna 206 comes to mind as being the smallest aircraft I can think of offhand that might be able to do it, although getting the motorcycle up and through the double side door would be interesting. Check out http://www.kansasaircraft.com/Websites/kac/images/SpecSheets/Stationair_2013_206H_SD.pdf.

You're awesome, thank you for taking this seriously!!

taking the wheels off the bike, i bet i could jam a bike up in the rear double doors with the seats removed!  that's awesome, now its on the list of things to buy!!

@Terry Yes, a 206 works :-)

The question is incomplete without information about the range this aircraft should have. Pilatus in Switzerland is always fond to tell of one of their customers who bought not one, but three PC-12s for exactly this purpose, and has one plus a Harley-Davison motorcycle stationed on each continent of interest. The size of a PC-12 allows the installation of a crane, so loading and unloading of the motorcycle are simplified.

PC-12 side view, with open cargo door (picture source)
Obviously, even a PC-12 does not have the intercontinental range to go anywhere, but if you plan to stay within one continent, range is not an issue. Alternatives in this class are the Czech Aero 270 or the Cessna 208 Caravan. All use a PT-6 turboprop engine, and you will need professional maintenance to keep them flying, so using them does not come cheap.
A more reasonable alternative would be piston-engined, and here the Cessna 206 or 207 (which @Terry already suggested) would be a candidate. However, fitting the bike in will be a challenge.
If you want more internal space and are not afraid of antique taildragger airplanes, the Antonov An-2 or the Canadian DHC-3 Otter would also be a good and reasonably priced choice - however, maintaining one (and especially its radial engine) will also burn a hole in your pocket.

DHC-3 in Pensacola (picture source)

The question is what small light GA aircraft has a payload of
185 + 400 + 185 (ball park for the second passenger) = 770LBS
The second question is how far you want to fly and thirdly getting the bike into the plane. The list may include

Piper Saratoga (nice loading doors with the seats removed, rumor has it you can get a piano through the loading doors of a saratoga)
Beechcraft Bonanza
Cessna Caravan (with type cert) or Cessna 206 on the smaller side of their offerings
Piper Seneca (if you have a twin rating)
Beechcraft Barron

and the list goes on (these are just the common ones). Remember that you can always take a gain in useful load if you sacrifice fuel but this is highly dependent on how far you want to go. Removing the seats will buy you back some useful load but here in the US that will require a new weight and balance to be prepared for you by and A&P. This is a pretty common task but need to be done for the plane to be legal without seats. On top of that since most motorcycle weight is in the engine I would be very cautious when doing your W&B for the flight. I can only assume you will strap the bike in, in which case I would measure engine to CG for calculation purposes. You can also take a bit of a gain by draining the gas from the bike before flying. Since you are presumably going to an airport you will be able to gas it up again (possibly with 110LL...).
Continuing on from the above list you get into turbo-prop land, depending on cost that may be doable or not for you. Can you further define your mission to include both distance and budget, that will make a big difference.

I've never heard a Caravan called small or light before, they're turboprops that can carry 14 passengers

Agree. You might consider the 206 (StationAir) rather than the 208 (Caravan).

Agreed I will amend my answer as I now see you need a type cert for a 208 (I figured that it was under 12,000LBS) and could be flown with a PPL

Cessna 206. This plane has been to Alaska twice carrying a motorcycle.

QED.


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Why was the engine of the Ju-87 Stuka not replaced with a more powerful one?
Related to this question
Why did the Ju-87 Stuka have a siren?
I would like to know the reasons why they have not changed the engine of the Stuka when they realised it was easy prey for Hurricanes and Spitfires in 1942/43.
Couldn't they have replaced the engine with a bigger one?
It is a heavy aircraft, but certainly could have gone through some improvements in order to increase its speed and manoeuvrability.
Ok it is a bomber, not a fighter, but still...

The price to replace the engine would be too exspensive and not necessary.

@Ethan I'm not sure that expense was a concern for either side during wartime.

@egid not in straight cash terms perhaps, but there was only so much material to go around (particularly in Germany as things turned against them).  A choice to build something is also a choice not to build something else with those materials.

The Ju-87 Stuka did undergo engine change during its life.
The initial Ju-87A version used the Junkers Jumo 210, an engine, which produced 602 hp. This was almost immediately replaced with the Jumo 210D, which produced around 661 hp.
The first production version, the Junkers Ju-87 B-1 used a Junkers Jumo 211D generating 1,184 hp. Note this version had the fuselage and landing gear redesigned from the 87A.
The next major version, the Ju-87D, used a Jumo 211J delivering 1,401 hp, after briefly dabbling with Daimler-Benz DB 603 engines.
The final operational version of Stuka, the Ju-87G, used the Jumo 211J engine.
This is more or less the same path followed by other combat aircraft of the era. For example the Hawker Hurricane MkI used a Merlin III engine producing 1,310 hp, while the last major version, the MkIV used the Merlin 24 (or 27) engines, producing 1,620 hp.
However, the main thrust in engine change in the Ju-87 was increasing the payload, rather than increasing speed or maneuverability like the Hurricanes. For example, bomb carrying ability was nearly quadrupled from 500 kg in the B-version to 1,800 kg (max load) in the D-version.
Another reason was the aircraft design itself. It was designed to be a rugged dive bomber, and increase in speed would've done it no good (it is to be noted that the fixed landing gear added a lot of drag, though it was sturdy enough to mount a cannon) and it had limited maneuverability at the best of times when loaded (though it had good turn performance at low altitudes). The airframe had already reached its limit.
The only reason the Stuka served till the end of the war despite its limitations becoming apparent by the Battle of Britain was simply because no better replacements were available (though the process started in the early 1940's), though the Focke Wulf 190 took over some of the duties of Ju-87.

an unloaded stuka is VERY maneuverable. The problem is that any kind of slow unescorted plane is very vulnerable. especially if it is loaded with bombs.

@Markus Mikkolainen The stuka was a very good aircraft, which did what it was designed for exceedingly well. My point is that it was not designed to be a fighter and no amount of powerful engine would've changed that fact.

yes. a slow design is a slow design. it was used effectively atleast up until -44.

The engine was replaced when newer versions were introduced: The first production model (Ju-87 A) used a Jumo 210 with 690 HP takeoff power. This was raised in the B version to 1200 HP by switching to the improved Jumo 211. From 1941 the D version with the more powerful Jumo 211 J (1420 HP) was introduced.
But that is all besides the point. No powerplant would had made it faster than the contemporary fighters, not even a jet engine. The design placed ruggedness first, and as a consequence had a fixed landing gear which could be used on unprepared fields. The airplane had a lower wing loading than fighters, had the very effective Junkers Doppelflügel (offset flaps) and could turn much better, so it was not easy to shoot down. The downside was an inherently higher drag which could not be overcome with a bigger engine (which would had made the aircraft heavier).

Detail of the Ju-87 wing flaps from the operating manual (picture source). By using those, a Ju-87 could fly much slower and turn much tighter than contemporary fighter aircraft.
The idea was to optimize the Ju-87 for ground support and let the Bf-109s and Fw-190s take care of the fighters. This worked well during the Blitzkrieg of 1940 and on the Eastern Front when the airplane was used as designed. This is the same strategy the US Air Force uses for the Fairchild A-10 attack airplane. Being designed as a dive bomber, the Ju-87 airframe was very sturdy and robust. There are many stories of Ju-87 pilots returning with heavily damaged planes.

Battle damage on a Ju-87 (picture source)

Damaged Ju-87 wing (picture source)
Especially Hans-Ulrich Rudel used the Ju-87 with great effect. If you read his memoirs (Amazon link), you will learn that he once was surprised by fog and could not fly back to his base. So he landed on a road and taxied the 70 km back. He almost made it back to base; only an impassable railroad crossing could stop him from taxiing all the way home.
At several occasions, he landed next to a shot-down Ju-87 and took the crew onboard. Try that with a Hurricane or a Spitfire.
In 1944 he was chased by a Russian fighter pilot. His observer, sitting in the rear seat, facing backwards, could tell him every time what his opponent was up to, so he could evade the attacks successfully, flying close to the ground and at minimum speed, flaps down. Suddenly, the Russian fighter was gone: Unable to fly as slowly as the Ju-87, he had stalled and crashed. Later, Rudel learned that this had been one of the most highly decorated Russian aces. The Ju-87 with a skilled crew was more than a match for him.
After the war, he consulted Fairchild during the development of the A-10.

Thanks for the detailed diagram of the flapperon! I've been looking for a close-up image of the flapperon to build my RC model. Now I get a cross-section!

@slebetman: You are very welcome! It is important to get the gap between wing and flap nose right, and in a model airplane the gap should not be scaled as the rest of the airplane, but be a little bigger. Essentially, you want to scale it for the scaling factor of the local boundary layer between original and model wing.

Ah, Rudel and his stories. All the battleships and tops aces he destroyed single handed.

Yeah, I wonder if Rudel ever had any run-ins with Il-2s during his service...

Last sentence brings it home.  The Stuka was the A-10 of its day, and did its best ground support work in areas where air superiority was established.  It was never meant to be a fighter, even in the hands of an expert pilot.

@RobertDiGiovanni Rudel's autobiography tells of another pilot in his squadron who flew out after the mission of the day to hunt Russian aircraft. In mopst cases he came home with a kill but one day in 1943 he went missing …

Replace the engine with... what, exactly? Bear in mind that at low-mid altitude (definitely below 10,000ft) the Ju 87D had a more powerful engine than any Bf 109 until the autumn of 1943.
After mid-1944 every high-power engine generally had good high-altitude performance, with low-altitude performance being mediocre in the absence of MW 50 injection. Every such engine was needed in a Bf 109, even with Fw 190Cs or Bf 110s theoretically waiting in the pipeline somewhere.
The Ju 87 was quite manoeuvrable, and performance with a bomb is worse in airplanes regardless of their installed power or role. If the enemy makes you jettison your bomb s to dogfight them, even if you do so in a high-performance fighter-bomber, they have already won.
You need to understand that attacking ground targets and attacking planes entail rather contradictory priorities. Fighters need to fly fast and to climb well to bounce the enemy and to retain as much energy as possible over the course of the dogfight. Ground attack missions require planes to fly low and slow so as to find and prioritise targets properly. This means that most of the time ground attack planes are inherently vulnerable to fighters.
Thus to properly survive in a fighter-heavy environment a ground-attack plane needs to accelerate quickly to a speed approximately equal to that of a fighter and then be a reasonable match to their opponent in manoeuvrability and (very importantly) rate of climb so that repeated/successful bounces by the enemy fighters are not likely. They need to do so while carrying their ordnance, be it large guns in pods or bombs. These are extraordinary requirements and quite unreasonable ones at that, especially as the Germans had an inability to make very powerful engines in quantity from factors rather beyond their control. And of course if your performance is that good even with a bomb you have a plane that would make a wonderful fighter in a clean configuration so chances are many planes would be diverted from ground attack detail for this reason...

One can expand the question: why didn't they replace the Ju 87 outright? Well they tried that too, but invariably ran into one problem or another that had nothing to do with the 87.
The Me 210 was a fascinating aircraft. It had a window that ran down the nose of the aircraft so the pilot could see ground targets throughout the bomb run. It could dive at "reasonable" angles, perhaps 30 to 40 degrees, had useful dive brakes, retracting gear, very good performance and an internal bomb bay. It also was unstable, and required massive redesign before emerging as the 410 right as swarms of P-51s were showing up.
The Arado 240 was a similar design and had similar stability problems. It was also ridiculously complex due to a strange arrangement of the fuel tanks.
The Ju 88 was also equipped with glide-bombing capability, although with a much shallower dive angle. Much has been written about how this aircraft was ruined by the addition of this capability, but I'm not convinced this was the root of the problem, compared to indifferent engines and odd design criterion for defensive fire.
So they had all these aircraft that were supposed to either supplant or replace the 87, but none of them matured, while the 87 kept being upgraded. This is far from the only example; the German war diary is filled with similar stories from Bomber B/Jumo 222 to their entire tank production effort.


text:
Is there a list of all airways?
Is there a public and current (AIRAC-cycle 1509)  list of all worldwide victor- and jetairways (including the pertaining intersections)? I'm not searching for a graphical map of the airways, but more for a text file listing all items.

Sorry for the poor tagging, I couldn't find any suitable tag (there isn't one for "airway" or "intersections").

This is something that you can probably purchase from a supplier of air navigation data such as Jeppesen or Lufthansa, but I don't know of a free world-wide source.  The FAA also sells this type of data, but it is for the US (and other aeronautical agencies around the world probably do as well.)

http://aviation.stackexchange.com/questions/16171/what-is-a-navigational-fix-where-can-i-get-navigational-fixes-for-a-local-airpo/16174#16174 at the bottom of this answer there is a short paragrph about navigational resources. maybe that helps.

There is an FAA publication that I found several weeks ago (while looking for something else, of course!) that seems to be freely available and contains this sort of data for the US.  It's published on a cycle, and when I get back to my other computer I'll see if I can dig up the link.  The data is only for the USA, though, so it's a very incomplete answer to the question.

Airway data is published in each country by their respective regulatory authority. This is published as a part of AIP(Aeronautical Information Publication).
This page contains links to some of the sites having electronic AIPs. The relevant data can be found in Part 2- Enroute(ENR). For example, this gives the details for UK airways.
I don't think there is a worldwide list as the airways of each country is controlled by the respective government through regulatory body and this information is updated periodically (in cycles of 28 or 56 days).

If it's not for real-world use, navigraph.com publishes a regular database of  worldwide airways, navaids, airports, SIDs and STARS, etc.


text:
Why would the fuel pressure decrease during a climb?
When performing a climb in a SIAI-Marchetti SF.260 with a Lycoming engine, the fuel pressure decreased. Why would that happen?

You sure your asking about fuel pressure and not manifold pressure? Also, what makes you think this is specific to one type or manufacturer of engine?

Yes the fuel pressure decreases...we flew sf260fh and that is we encounters

Does that aircraft it have a fuel pump? If so, what drives it and was it on or off?

Are you asking a general question of drop of fuel pressure or a particular event that occurred? Generally speaking it is normal that the pressure of fuel decreases with altitude, at one side fuel tanks are at atmospheric pressure, and at the other end of the fuel lines the engine has an internal pressure (suction). So the tank side pressure varies with ambient pressure.

The most obvious answer is "Gravity".
To some extent this is "normal" in a low-wing aircraft with a nose-mounted engine and a fuel pump drawing fuel from the wing tanks into the engine: As the nose pitches up the fuel needs to run "uphill" to get to the engine - that's more work for the fuel pump, which might not maintain full "straight-and-level" fuel pressure.
You can see something similar in a Piper Cherokee in an aggressive climb, particularly if you are only using the engine-driven (mechanical) fuel pump: The fuel pressure typically drops when you pitch past ~15-20 degrees nose-up. The drop isn't much, but it's noticeable if you're looking for it.
If the pressure drop makes you uncomfortable turning on the electric boost pump(s) may reduce or eliminate it, but as long as the fuel pressure remains in the aircraft's normal operating range it's probably not a cause for concern. You should however become familiar with how much the pressure tends to drop in a climb: A larger drop than "normal" may indicate a problem with the (mechanical) fuel pump which you would want to have your mechanic investigate.


text:
As a Brazilian pilot, can I buy an aircraft in the US then fly it to Brazil to register it?
I have a pilot license in Brazil and would like to purchase an aircraft in the US and then register it in my country.
My license allows me to fly the aircraft back to my country?

If you agree with my edit to your question, please see this article: Importing and Exporting Aircraft

Are you asking a) what regulations are there on exporting an aircraft from the US, or b) can I fly a US-registered aircraft to Brazil using a Brazilian pilot's license? Those are different questions.

I'm not sure if you're asking about general export regulations, in which case Farhan's link is useful, or the more specific licensing question.
But regarding licensing it's clear that you may not fly a US aircraft from the US to Brazil with only a Brazilian license. 14 CFR 61.3 says:

(a) Required pilot certificate for operating a civil aircraft of the
  United States. No person may serve as a required pilot flight
  crewmember of a civil aircraft of the United States, unless that
  person:
(1) Has in the person's physical possession or readily accessible in
  the aircraft when exercising the privileges of that pilot certificate
  or authorization—
(i) A pilot certificate issued under this part and in accordance with
  §61.19;
(ii) A special purpose pilot authorization issued under §61.77;
(iii) A temporary certificate issued under §61.17;
(iv) A document conveying temporary authority to exercise certificate
  privileges issued by the Airmen Certification Branch under §61.29(e);
  or
(v) When operating an aircraft within a foreign country, a pilot
  license issued by that country may be used.

In other words, you can use your Brazilian license to fly a US aircraft in Brazil (see 61.3(a)(1)(v) above) but otherwise you need a US license or a special authorization (61.77 covers leasing and commercial operations so it almost certainly won't apply to you).
I know very little about this, but at least in theory it looks like your options are:

Get a US license yourself, perhaps a foreign-based license based on your Brazilian one (see 61.75)
Get some special permission from the FAA
Pay a ferry company to fly or transport the aircraft to Brazil
Register the aircraft as Brazilian before it leaves the US (this may not even be possible)

And those are only the FAA/aviation issues, you have to think about customs and general import/export regulations too, both in the US and Brazil. I would look for some specialized help with this.

Or hire a pilot to fly the first part of the flight (in US air) and put him on an airline back home after you land in Brazil.

Where does it exclude a Brazilian license from those paragraphs? I don't know, but can imagine there being a treaty or agreement that would have a Brazilian issued license be valid in the US under e.g. par. 61.19

@jwenting The FAR I quoted lists 5 certificates or authorizations, any one of which is valid to pilot a US aircraft. (i) talks about US licenses ("issued under this part", i.e. part 61); (ii) refers to an aircraft leased by a non-US citizen; (iii) is for temporary certificates issued after a test while you wait for a permanent one; (iv) is about lost/damaged licenses; (v) allows foreign licenses but only "within a foreign country". Foreign licenses are not valid in the US for N-reg aircraft; the closest thing is a foreign-based license issued under 61.75 (I added that to my answer).

@TylerDurden The question is about flying a US aircraft, not a Brazilian one. And I did indeed suggest the (probably impossible) option of re-registering it as Brazilian while it's still in the US so that the license would match the aircraft.

@Pondlife my mistake, on re-reading it looks like your answer covers all the bases

why would it be nearly impossible to reregister to at least a temporary Brazilian registration while in the US? AFAIK that's pretty normal for exporting aircraft, especially if the US FAA indeed doesn't allow people with a foreign license to fly US registered aircraft even for exporting them.

@jwenting To be honest I probably shouldn't have said that, since I'm really just speculating about the difficulty of dealing with a 'remote' bureaucracy. I have no idea if Brazil allows it or not.

With a foreign license you are only allowed to fly aircraft which are registered to the same country as your license in foreign countries. This is the way the international treaty system works.
So, to fly the plane out yourself legally, you would have to get it registered in Brazil somehow first, or get some kind of special permission.
One type of permission is called a "special purpose pilot authorization" (see 14 CFR 61.77). You may be able to get such a special authorization for a one-time flight, even if the aircraft is US registered. If I were you, I would call up the FAA and ask them about it.


text:
How can take-off slots suddenly become available even when airspace is congested?
Here is something that happened to me: my flight was 3 hours late because the plane arrived late. We were told that a further 3-hour delay was expected because our flight had lost the slots it had in the air traffic system, and we couldn't immediately get new slots due to very high congestion in the skies.
Nevertheless, all the passengers were immediately boarded, all the flight procedures were initiated (safety film etc.), the plane taxied towards the runway and immediately departed.
After landing I asked the pilot how the 3 extra hours we had to wait due to congestion suddenly "disappeared". He told me that congestion is fluid and sometimes things change.
How can things change so much so quickly? Is the pilot's explanation plausible or is there another story behind what we were told by the airline?

maybe some other plane was late, like yours?

Very interesting question but i think it is too broad to be answered here.

When you have some resouce, be it landing slots or slots for some piece of airspace, that is slot controlled, it works a little like seats for a movie theater.  If few people (flights) have reserved tickets, you show up & get your ticket (slot) right away & all is good.  If everything is taken, you show up & get told you'll have a wait.  BUT, if not everyone with a ticket (slot) can make it on time (say, another flight is delayed for MX), then that seat (slot) is now available for you, and your wait wasn't as bad as it might have been.

Perfectly fair question, and while we probably won't conclusively determine THE exact details of the OP's situation, a discussion of slots and how much they can flex -- as was asked -- is entirely reasonable and not at all overbroad or unanswerable.  Voting to reopen.

It would help if you would share information on the route you were flying on.

In that case it sounds similar to What are the differences between "ground stop", "ground delay", and "gate hold"?

It's a very credible explanation.
Slots to allocate scarce ATC and airport resources are created based on a known rate at which the airport/airspace can handle traffic, and they are apportioned out based on things like when the flightplans are filed, allowing for time enroute and expected arrival times.  (This is a little general -- trying to give a big picture without getting mired in too many specifics of EDCT's, Ground Delay Programs, and so forth -- some of those details can be found in answers to this question.)  When total demand is below capacity, it's common to be told to "contact Clearance Delivery 5 minutes prior to Push for your wheels up time to XYZ," and then on calling Clearance, you're either given a wheels-up time in about 15-20 minutes (i.e. push on time, taxi out, and take off with no delays) or even "released with no restrictions."
However, when demand is greater than capacity (most common when a bottle-neck is caused by something like bad weather at the destination reducing the allowable arrival rate, although also caused when a runway or an approach is unusable for some length of time), then things start to slow down, and you may be given a wheels up time farther off in the future.
Better to sit at the gate not burning gas than burning gas at idle out on a taxiway, or burning a LOT of gas holding in the air, but not most flyers' idea of a good time.
When things are HIGHLY saturated, as it sounds like the OP's scenario, you can't get your slot time issued until you are actually ready to go, but you (or your dispatcher) may have a sense for what sort of delay is likely.  In these cases, you often can see where some aircraft have been given a significant delay, and anticipate something similar -- but you don't actually know what you'll get until you call.
Sounds like the crew for the OP's flight anticipated that they MIGHT be pretty far back in line, and explained things accordingly, but when they actually called then either conditions had improved, OR a particular slot was available (perhaps another flight had cancelled or been delayed) and they got it.  That's not all that uncommon -- you call for your time, hoping for the best & prepared for the worst, and sometimes you get the "wheels-up" time 90 minutes out, and sometimes you get "can you be wheels up in 12 minutes?" and if the answer's "yes" then there's a quick high-five in the cockpit and "tell 'em to shut the door, we're going!"
Due to the lead times involved, when a slot opens up like this, ATC typically does NOT call every flight "in the queue" to shift everybody forward by 5 minutes; that slot either gets used by somebody, or it's just unfilled.  But when we've told our passengers "you can get off the airplane, be back by X so we can leave," making adjustments to that X time isn't practical, so for us that time is pretty well set.  Somebody else who IS boarded up & ready may get that fallout slot ahead of us, and when he does, good for him.

It may all also depend on where the bottleneck is. The pilot may think they will get a long delay because the other two flights got long delay, but the bottleneck may be somewhere enroute where they are going but you are not. Or the dispatcher may come with a different routing for your flight that avoids it.


text:
How is it safe for helicopters and Ospreys to refuel in mid-air?
How do military helicopters like the Blackhawk and CH-53, as well as the V-22 Osprey, perform mid-air refueling without their rotor blades (periodically and accidentally) contacting the drogue or fuel hose and causing a major accident?

I imagine that if the rotor blades did make contact with the fuel hose, either the fuel would be released and be sparked and ignite, or ingested by the helicopter turbines, or the rotor would break, or all of the above!  When a helicopter is refueling, its rotor is nearly above the fuel hose, or at the maximum, maybe 20 feet away?  It's easy to imagine a bit of turbulence or a few centimeters of cyclic movement (a sneeze perhaps?) is all that it would take for the rotor to dip and come forward and contact the hose.
For the Osprey the propellers / rotors are behind the nose of the aircraft and thus farther away from the fuel hose, but still, like a helicopter the Osprey's rotors are very large, and are exposed as opposed to the concealed compressor blades of a jet turbine.

when an osprey would refuel in flight it would be in the level flight configuration (rotors pointing forward)

You seems to be under the assumption that inflight refueling is safe. It is'nt. It's merely "safe enough"

That photograph distorts the perspective.  Just Google for "helicopter air-to-air refueling" and look at the image results.  Many show other perspectives from which you can see that it is not possible for the blades to contact the hose or basket - the probe is longer than those on a fixed-wing craft for exactly that reason.

This video shows a CH-53E Super Stallion chopping off it's own probe through over-controlling the cyclic, but that particular mishap would be possible in other flight phases too.

woah crazy video.

It's pretty amazing to me that the rotor survived hitting the probe.  You think they designed the probe to be easily broken in a case like that, so as not to break the rotor?

The probes are designed to snap easily if there is significant lateral or vertical force.  For sure, the rotor would have been damaged and they would know all about the vibration but blades are tougher than you think.  They can chop the tail clean off on some helicopters.

When fully extended the probe does extend past the rotor of the HH-60G; however, there is a potential for the probe not to extend. And in that case, the probe is well inside the rotor disc. Still, refueling can still be accomplished.  Just like single-engine refueling, it takes more care but when you need fuel you do what you must.  And in my 20 years flying the Pave Hawk I never found the switch for an IR sensor on the probe :) no such thing.  Closest thing I can think of is using the probe light barely cracked on (it’s controlled by a rheostat) to cast a shadow on the drogue during NVG refueling but in a tactical environment even being that much of an emitter is unwise.

The probe is the furthest point forward on the Pave hawk helicopter. It also has an IR sensor to properly line up the boom(the female end). Obviously the procedure for approach is to come from behind to avoid such things from hitting the rotor blades.


text:
Do some modern VORs not spin?
Today in Ground School we learned about radio navigation. I read here that the rotating part of the VOR rotates at 1,800 RPM (wow! Is it an electric motor that spins it?)
We know that modern Active Electronically Scanned Array radars are able to send signals in different directions without physical moving but instead steering the signal electronically (by selectively delaying some of the signals precisely).
Do some modern VORs implement a similar technology and use this to rotate the signal 360 degrees instead of physically spinning?

There are no spinning parts in the VOR.
It typically uses 60 antennae in a phased antenna array to steer the beam in a rotating sweep.
The VOR transmits a constant omnidirectional signal.  The phase of the secondary sweeping directional beam is varied in time such that it is out of phase with the constant signal by the same number of degrees from North.  The receiver measures the phase difference between the constant and sweeping signals to determine its bearing from the transmitter.

While the phase of the variable varies, it is not varied in the VOR itself, but it's an artifact of Doppler effect (so the name Doppler VOR). There is no sweeping directional beam, but two omnidirectional signals sent by two opposite antennas, the pair of active antennas being changed so that the entire array is scanned 30 times per second. These two antennas just send a fixed frequency, the Doppler effect does the rest. These signals are the sidebands and the carrier is sent by the central antenna, so in total there are three omnidirectional patterns.


text:
Are US pilots permitted to carry & use their firearm in countries where guns are illegal?
On the question of Are pilots armed?, one thing this made me think is: for the few that are armed, are they allowed to bring their weapon into, for example, the UK?
What is the procedure? Does the gun stay in the cockpit or does it need to be checked by security once on the ground?
Presuming a pilot had to fire a gun over EU airspace, is he breaking the law?

@casey Looks like it comes under 44921§b.3.J

Those laws can get amusing.  I don't know if it's still the law, but at least in the past it was required for private pilots to carry a gun in the airplane in Alaska.  Where I live, it's long been illegal to take a gun onto the airport property.  Not sure how one was supposed to fly from here to there.  :-)  Stop partway there and buy a gun???  :-)

@BrianKnoblauch yes, or there was a clause that allowed flights not originating within the state to fly without a gun on board (thus giving you time to buy one locally).

Once you land you have to abide by the laws where you are. In the US federal laws (if there are any), when flying in US airspace.
Most US laws about airports and guns, only apply to the secured space. (Inside security), not the GA ramp or anyplace else.

Can you leave the gun in the plane in a country where it's illegal, or do you have to remove it before the flight?


text:
Have any passengers crashed planes?
The question Are pilots allowed to let passengers fly the plane? is interesting to read, noting that pilots are permitted to allow passengers to fly.
I recall an Air Crash Investigation episode (AFL593) where the pilot pretended to allow his son to manipulate the controls of an airliner, without realising the autopilot had been disconnected, resulting in an accident.
I'm wondering how commonplace this is? Is this an isolated incident?
On the flip-side, I've heard of at least 3 occasions where passengers have successfully landed planes, e.g:

@fooot Yep, that's the one!

I wonder if this questions would be more appropriately titled "are passengers allowed to fly commercial flights under the direction of the flight crew?"  The title, as it stands, is clearly answered by the question itself.

@DannyBeckett The second link you have is a song?

@Farhan The link is to a recent documentary: Mayday! The Passenger Who Landed A Plane

Passengers are not allowed to fly a commercial plane. The question you reference says that a passenger can take the controls on a private flight only.

@Ben As I mentioned, it's happened at least once. I wanted to know if there were any other recorded accidents like it.

Sorry Danny you may have misunderstood me. Your question is a good one as it has happened at least once. But the first line of this question says "noting that pilots are permitted to allow passengers to fly". Which is not entirely the case - they're only permitted to fly if it is a private flight, not a commercial one.

Please fix the links.

@CarySwoveland Sorry about that, the link I watched "Mayday! The Passenger Who Landed A Plane" on seems to have gone down. I've replaced the link with a different instance of a passenger landing a plane. If you can find it online, it's well worth a watch. It was unrelated to the popular air crash show Mayday. I believe it was BBC, though it could've been any UK TV channel.

I was interested and did watch other accounts of the crash. "Passenger Who Landed a Plane" isn't quite accurate, unfortunately.

If I'm not mistaken, AFL593 crashed because of a bug in Airbus firmware which disconnected autopilot (without warning the pilot) after 2-3 strong yoke's moves, made by that kid. Kid did not turned off autopilot himself. Father (pilot) let his son to pilot the plane, only because he was 100% certain and sure, that kid will not actually pilot the plane, due to autopilot being engaged. That was the conclusion from mentioned ACI episode. In this case, I wouldn't call AFL593 an example of passenger crashing commercial plane at all.

@trejder I don't believe that's correct. AFAIK, it was not a bug in firmware, it was an intentional design feature to disconnect the autopilot if the pilot was supplying control inputs that conflicted with the autopilot's (on the theory that the pilot probably knew what they were doing, and they didn't want to do what the A/P wanted to do, so the A/P should yield control). It didn't act like the crew expected, but it acted like it was designed to act.

@cpast I cannot address Airbus firmware or design issues, because this is not my area of expertise. And I can hardly address mentioned ACI episode, because I watched it about 5 or 6 years ago. But. from what I still recall from watching it, even if that was a design feature, the fact, that there was no visual indication, that A/P is disengaged, is an obvious feature or design flaw. And it sounds logic even too me, just a mere passenger. If something is on and it is so important, that entire flight safety depends on it, the I should be visually warned once that thing goes off.

@cpast I'm more than sure, that there would be no trouble on-board and no crash at all, if pilots would be informed visually immediately after A/P was switched off. Their surprise (recorded) about plane movements clearly  suggests, that they were very surprised and didn't know, what is going on. Therefore, I must again claim, that this particular air crash was IMHO much-much more based on design flaw and has merely nothing about passenger crashing a plane. But, that's just my opinion and you're free to disagree with it.

@trejder: AIUI there is a visual indication of the change in autopilot status (which isn't simply an all-automatic or all-manual choice). Wikipedia says " A silent indicator light came on to alert the pilots to this partial disengagement. The pilots, who had previously flown Russian-designed planes which had audible warning signals, apparently failed to notice it." See http://aviation.stackexchange.com/questions/390/did-airbus-add-an-audible-alert-when-the-autopilot-partially-disengage-after-the

A distinction between cases where the pilot let a passenger take control and cases where a passenger takes control with force might be relevant. I recall four incidents a little more than a decade ago in which passengers took control of a plane and crashed it. All four incidents happened within a day.

Passengers don't even need to enter the cockpit to create problems

Do you count hijackings resulting in the hijacker crashing the plane?

Some years ago a KC-135 crashed during an aborted takeoff.  Turns out a civilian with zero flight experience was in the co-pilot seat. Totally against regulations of course, but there you are. The civilian did not cause the accident but there was no qualified pilot in the seat when it counted most.

No passengers have crashed an airplane while the pilot was letting them fly.
In this situation, the PIC crashed the plane because he didn't do his job as the captain and final authority for the safe operation of the airplane.
Letting a passenger fly would most likely be listed as a "contributing factor" by investigators looking into an accident where this happened, but responsibility for the crash lies squarely on the PIC.

'tis a fine mincing of words, worthy of the most gourmet attorney -- yet it is also correct (in so far as the FAA, NTSB, and Insurance company are concerned)

This answer is noteworthy, but doesn't actually touch on the question itself.

Hey, it answers the question in the title!  ;-)

At what point does responsibility begin to attach to the person manipulating the controls? Is the PIC fully responsible for the SIC's ability to control the aircraft? If not, is the threshold that the person on the controls was licensed to operate that aircraft in those conditions, or is it something else?

@cpast Yes, the PIC is responsible for taking over control of the aircraft if the SIC is not capable.  The PIC is always responsible....

@Lnafziger: Unless the PIC becomes incapacitated, in which case responsibility defaults to the SIC.

Responsibility is besides the point. The PIC may be legally responsible, but the person crashing the plane (this was the question) by his actions may still be the passenger, not the PIC.

Please see the transcript of Aeroflot 593
Overview: The pilot allowed his 12 year old and 16 year old children into the cockpit to sit in the pilot's seat of an Airbus A310. The older child's actions disconnected the autopilot. All aboard were killed when the crew was unable to recover from an unusual attitude after the autopilot disconnect.

Another possible passenger-caused accident is the death of Thomas J. Stewart and his family in a Eurocopter EC135 in Phoenix. Stewart allowed his 5 year old daughter to sit in his lap during the flight. The NTSB concluded that the daughter kicked the controls and that the pilot's recovery attempt severed the tail. Both Stewart and his daughter were passengers and may have caused the accident with their actions.

This isn't really an answer to the question. AFL593 is the flight which the question was referring to in the first place.

Plus: this answer in inaccurate. See my comment to question itself.

There was a passenger who crashed an light aircraft over Bodensee in Austria. Psychological factors were assumed to be the reason the passenger forced the controls forward crashing the plane into the lake. He and the pilot were killed.
Source: Der Standard (in German)

I recall an Air Crash Investigation episode

Aeroflot flight 593 Moscow–Hong Kong, Airbus A310-300, Russia, 23 March 1994

where the pilot pretended to allow his son to manipulate the controls of an airliner,

The pilot actually allowed his son to manipulate the flight controls. The A310 has a conventional yoke.
The autopilot was engaged at the time, so small movements of the flight controls had no effect. The pilot pretended to his son that he was in full control.
Large, forceful movements contradicting the autopilot caused the autopilot to relinquish control to the pilot (the autopilot assumes the pilot knows best) - in this case, control over ailerons (but not over pitch, airspeed, altitude, throttles etc).
Pilots are not dropped into new aircraft without training to understand how use of the controls affect the autopilot. The pilot's actions were reckless and he failed to monitor the childs actions and their effects.

A310 cockpit - Image source

without realising the autopilot had been disconnected

The appropriate indicator light illuminated to show that there was manual control over ailerons but it seems the pilot was too busy entertaining his child to pay proper attention to flying the aircraft.
The "cavalry charge" audio alert only occurs when the autopilot is fully disengaged.
lights on the instrument panel show what aspects of flight the autopilot is controlling.
It was actually the child who first noticed that the aircraft was banking!

resulting in an accident.

In combination with inappropriate actions by panicing pilots.

Despite the struggles of both pilots to save the aircraft, it was later concluded that if they had just let go of the control column, the autopilot would have automatically taken action to prevent stalling, thus avoiding the accident.[11]

(Wikipedia)

I'm wondering how commonplace this is?

It seems to be very uncommon for children and/or other passengers to enter the cockpit midflight and cause a crash.

Is this an isolated incident?

No. See dawg's answer. It may be the only case on an Airbus.

IMHO this incident is more about the obtuse complexities of the autopilot than the kid. I am stunned to think the pilot let the aircraft get out of normal flight parameters like that. In my day if the autopilot did anything unexpected it was disconnected immediately. We never let the autopilot "take us for a ride." Or, conversely, assume that is would save me from the other pilot.


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Are there any EU/EASA regulations surrounding aviation software?
A great question's been asked: Is there any U.S. / FAA regulation that could apply for aviation software?
This is interesting to me as a programmer and aviation enthusiast, but being based in the UK,  I'd like to know if there any EASA regulations surrounding the creation of software for use in the aviation industry?

I think you should specify which branch of aviation you mean. For example I work in company which develop software for airline. Single airline has many departments and each of it works on different regulations (operations, ground handling, scheduling, continuing airworthiness etc). You may also mean A/C installed equipment software.
There is no simple answer on whether there are regulations for aviations software or not. It depends on aviation branch.

If we speak about airborne software, the main document is the RTCA/EUROCAE DO-178/ED-12 currently at the "C" version: Software Considerations in Airborne Systems and Equipment Certification: if you want to certify (and thus commercialize) your software for flight, this is the main document to read.
Depending on the scope of the software and the design/development process there might be different supplements (see here):

DO-330 Software Tool Qualification Considerations
DO-331 Model-Based Development and Verification Supplement to DO-178C and DO-278
DO-332 Object-Oriented Technology and Related Techniques Supplement to DO-178C and DO-278A
DO-333 Formal Methods Supplement to DO-178C and DO-278A

It has been prepared by the RTCA/EUROCAE joint committee and approved by both FAA and EASA under different names, but the content is the same.
As @Greg mentions, these documents are not freely available

The DO and ED documents you refer to are RTCA resp. EUROCAE documents, not FAA/EASA. Also they are standards, not regulations.

@DeltaLima I say that are the "main document to read". Also they are not coding standards.

Two relevant standards from EUROCAE (European Organisation for Civil Aviation Equipment) are:

ED-109A / Guidelines for CNS/ATM Systems Software Integrity Assurance
ED-153 / Guidelines for ANS Software Safety Assurance

Unfortunately these documents are not freely available. However, you can find some information about the contents of these documents from other sites, such as LDRA.

These are standards, not regulations.

If you asked about the regulation my answer would be FAR25 25.1301 and 25.1309 for large aircraft software. DO-178C is recommended as a means of compliance by AC20-115D. Software review and approval guidline can refere to FAA Order8110.49 A and EASA CM-CEHSW-002.

EASA has published a memorandum with guidance on how to comply with the certification requirements. It is based on EUROCAE ED-12B/RTCA DO-178B, but is more specific.
It is called EASA CM - SWCEH – 002 and you can find it here.


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How are jet engines certified against birdstrikes?
I recall that during US1549's birdstrike incident that resulted in it landing on the Hudson, a large amount of migrating geese weighing upto 20lbs each were sucked into the A320's engines — far bigger and heavier than previously certified.
I believe that at the time the engines were tested & certified by throwing small chickens or similar, one at a time, into the engines. Has this certification process been improved at all since this incident?

https://www.youtube.com/watch?v=4nAc7wab-l4

GE90-115B certification

Calvin and Hobbes teaches us that engineers drive progressively heavier trucks over bridges until they collapse to determine what the structural load limit is ("Weigh the last truck that made it and build an identical bridge"). Why shouldn't bird strike certification be the same: Throw progressively larger birds at the engine until it blows up (or you've shredded an Emu)!

I believe they actually use mammals, starting with naked mole rats and working up to baby elephants.  The higher bone-density means that if an engine can withstand a human (or equal) sized mammal, then a bird of that size will be even less stressful.

The bird strike occurred on January 8th.  Which way were the geese migrating?

@SpongeBob: It also means that the engine can avoid blowing up if it eats a human, which happens from time to time and is generally a bit bad for the human ingested.

There are hundreds of tests that need to be performed for certification of a turbine engine.
The FAA requirements and tests are listed in CFR part 33 E and F.
Amongst them are:

Maximum static thrust tests
Vibration tests
Endurance tests
Water ingestion test
Hail ingestion test
Ice cloud test
Bird strike test

A number of them can be seen in this video of the GE90-115 Engine
The specific requirement for bird ingestion are described in §33.76. The number of birds to be used and their weight depends on the area of the engine inlet.
There have been several changes to the bird ingestion requirements for certification since the A320 engine was certified in 1996. However, once an engine is certified there is no need to demonstrate compliance to the updated requirements; the engine remains certified as it was.
The latest update to these requirements was in 2007, prior to the Hudson accident. To answer your question: no, there have not been any changes to the bird strike testing requirements of engines in the aftermath of the Hudson accident.

Actually, reading the NTSB report, changes were made regarding bird ingestion certification, after the certification of those engines. Also, the NTSB recommends ... the FAA specifically reevaluate the 14 CFR 33.76(d) large flocking bird certification test standards

@DannyBeckett That is a recommendation. Recommendations take time to be followed up, if they are followed up at all. Changing certification test standards is not done overnight. It is a long process of debating and reviewing requirements with a committee of experts from industry and government.

Sure, but the report specifically mentioned in verbose detail, that the certification requirements had already been changed.

@DannyBeckett but if you look up 33.76, you see that the latest amendment was in 2007, prior to the accident.

From memory though, these particular engines were certified under the 1996 standard.

@DannyBeckett probably true. Once something is certified it needs not to be recertified if the certification requirements change afterwards

let us continue this discussion in chat

I'm going offline for 8 hours or so now, but I'll catch you in chat in the near future. Perhaps somebody else will weigh in with their opinion in the meantime, either way.

@DannyBeckett ok, enjoy your day, we'll talk later.

There are multiple various requirements, for instance:

After "swallowing" a smallish goose (formally up to 3.65kg) the engine must still pull at least half of the thrust for at least 14 minutes, and must not become dangerous for the plane (no fire, no uncontained failure).
After ingesting a flock of ducks (16 birds no more than 0.85kg each) the engine must still work for about 20 minutes.

There are also requirements for various sizes and number of birds in between, and some requirements depend on the inlet size. In general, seems that after the bird strike the engine is required to stay safe and even work for some time, but not for long.

Your example birds were say off the mark so I've edited. 3.65kg is not a "fat goose": it's at the bottom end of the weight range for Canada geese (2.5-6.5kg). A sparrow weighs nothing like 850g: in fact, they weigh about 25-40g.


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Can you have an AME also sign off on your FAA BasicMed paperwork?
It seems that you should be able to have an AME sign off on your First, Second, or Third Medical and also do the BasicMed exam at the same time.
If you are older, like me, the Third Class Medical would be in effect for two years and when it expires, I can take the course to extend the Basic Med for two more years. I could exercise the privileges of the Third Class Medical (e.g. fly to Mexico) for two years and then continue to fly under the restricted privileges of BasicMed for two more years.
As far as I can tell, getting the BasicMed paperwork doesn’t invalidate the other certificates and getting a Third Class (or higher) Medical doesn’t invalidate your BasicMed.
Is anyone aware of any FAA (or AOPA, EAA, etc,) guidance on the issue?

From the FAA's FAQ:

Q35: Can my AME provide the medical examinations under BasicMed?
A:
  All AMEs are state-licensed physicians and may elect to conduct
  physical examinations required under BasicMed. But the FAA does not
  require AMEs to provide medical examinations under BasicMed. It is up
  to the individual AMEs to decide whether to offer BasicMed medical
  examinations based on medical practice considerations

The key words in there are "may elect to". There have been several discussions about this on AOPA's forums (members only) and people's experience so far is that most AMEs won't do BasicMed. The only specific reason I've heard is liability: one explanation I read is that when acting as an AME, the physician is representing the federal government and is therefore more or less immune from liability. But if he does a BasicMed exam he's acting as a regular state physician, and his liability insurance may or may not allow it. So you just have to ask your AME if he'll do BasicMed or not.
As for whether BasicMed affects a third-class medical or vice versa, this is from the same FAQ:

Q2: How does BasicMed affect FAA medical certificates? Does FAA still
  offer the third class medical?
A: BasicMed does not affect medical
  certificates at all and did not do away with third-class medical
  certification. In fact, third-class medical certification is still
  required for GA aircraft and flights that do not meet the criteria for
  BasicMed. Nothing about the FAA’s medical certificate program has
  changed with BasicMed, and you can still apply for a first, second, or
  third class medical the way you always have. BasicMed is merely an
  additional qualification you can use to fly, in lieu of holding a
  medical certificate.

And this:

Q6: Can I exercise BasicMed and hold a medical certificate at the same
  time?
A: Yes. If you are operating under BasicMed, then you must comply with
  the BasicMed operating limitations (e.g. flying only within the U.S.
  and at or less than 250 knots). When operating under BasicMed, you are
  not exercising the privileges of your medical certificate.

Simply put, there is no link or dependency at all between an FAA medical and BasicMed. Your AME might do one physical exam and sign off both at the same time for the sake of efficiency, but that doesn't change anything about the renewal dates.

I know that some AMEs will do both. Both of my brothers just got Third Class and BasicMed from an AME. He didn’t know what the rules were for priority though. That’s the reason for the question.

Part of the question is not answered, though. Can he sign off on 3rd class and BasicMed at the same time so that they run concurrently, or would be have to get another BasicMed exam when his 3rd class runs out?

@TomMcW Good point! I've updated my answer. In my defence, I answered the question in the title, not the question in the body :-) Hopefully now it covers both.

If the AME is likely to sign you off for the third class medical, then they would likely sign you off for BasicMed.  Talking with AMEs and various practicing physicians, I have come to the opinion that using your primary care doc, or an industrial medicine doc who does work related physicals may be your best bet for BasicMed.
You can decide which medical certificate you are utilizing for a given operation.
The AME can sign off more than one physical concurrently, with no need to perform more than one examination.  That question was recently addressed at an AME refresher.

Based on "Q6" quoted in Pondlife's answer, it seems that the pilot doesn't necessarily get to decide which certificate to use for all flight ops.

BasicMed can only be used for eligible operations.  If one is conducting an operation that requires a third-class medical and is not satisfied by BasicMed, then only a third class medical may be used. If you mean something different, I am not following you.


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Precision Approach systems: Why is ILS used more frequently than PAR and MLS?
I have studied that the main three systems for performing Precision Approaches (PA) are the ILS (Instrumental Landing System), PAR (Precision Approach Radar) and MLS (Microwave Landing System).
However, in most of the airports the ILS is implemented as the main PA aid; while the others are often developed, but not fully implemented or unused.
Questions:
What's the reason that the ILS is the most popular PA system?
What are the benefits and disadvantages of the other systems for not being as much considered?
How do they compare regarding approach performances?

ILS is significantly cheaper than PAR (in time and aircraft that can land per hour) and than MLS (in hardware). Anything ground- or controller- based is going to be expensive. You should be asking why LPV or other precision GNSS (satellite-based) approaches are not more popular than ILS!

Also, this is three questions in one, and it reads a bit like a (slightly outdated) homework assignment. Are you still in flight school, by any chance? :)

Well it's not homework. Just I'm interested in knowing that. I did three questions because they help compare the systems, sorry if it sounded like an assignment. And I know that LPV or GNSS based approaches cannot attain a higher level of precision (maximum precision is ILS CAT-I) that's why I asked the third question.

Ok! Wasn't accusing, just curious. You are right that LPV is not certified to CAT-I standards but it's certainly more precise (and more common) than PAR, and I have only heard of one MLS approach existing in the world, a curved one in Alaska. There may be more, but it is ultra rare.

Okay thank you for the info :) I was asking about those systems because appeared on my book and it didn't provide a lot of information and I wanted to know the differences. That must be the reason, that they are more rare to find.

At least in the U.S., ILS is popular because it is popular. It's relatively cheap to install and operate, the receivers share technology with VOR, and it is already installed everywhere. Momentum (and cost of replacement) has a lot to do with the failure and success of navigation systems.
MLS requires new hardware on the ground and in aircraft. The FAA tried to roll it out in the U.S. in the 80s, with a goal of replacing ILS by 2010, and utterly failed. The equipment was expensive for aircraft and ground facilities, and the cost of developing the approach procedures was high, as well as each approach needs tailored antenna programming (ILS is reasonably standardized). The adoption rate was low and the benefits (better arrival area guidance, better accuracy in some cases) were duplicated by the much cheaper GPS.
Precision GPS (LPV or LNAV/VNAV approaches) only appeared with the development of the Space Based Augmentation System (SBAS), also known as the Wide Area Augmentation System (WAAS). Augmented GPS has higher vertical precision and allows a single navigation system to be used for enroute, terminal, and precision approach guidance, a huge cost savings. The relatively new Ground Based Augmentation System (GBAS, originally called LAAS) adds high precision approach capability bringing GPS approaches closer to ILS and MLS.
PAR exists, but you may misunderstand what it is: it is a controller staring at a radar scope and issuing pilots instructions. It's stressful for pilots and controllers and very time consuming. Outside of military facilities you would be hard pressed to find a place to practice a PAR these days, at least in my experience.
In order of precision, high to low:

MLS
GPS with GBAS (uncommon)
ILS
GPS with WAAS (common, aka LPV)
PAR

In order of (estimated) total cost, high to low:

MLS (very expensive install + unique approach design + maintenance)
PAR (relatively cheap install + costly workforce; educated guess on my part, could be cheaper than ILS?)
ILS (expensive? install + simple approach design + maintenance)
GPS with * (no install, simple approach design, no obvious maintenance)

Thanks so much for the answer, and yeah I was misunderstanding what a PAR was, now it's much clear and I can see that is stressful and time-consuming. Good answer!

I would think that PAR is cheaper then ILS... As far as I know it is "just" a "more sensitive radar", and those are installed at bigger airports anyway (for example for ground operation and guidance)... In other words, PAR approaches (as I was told) are in most cases only a by product and the equipment has another function it is used for as well. Good comparison though!

@Maverick283 It's not just more sensitive radar; it's significantly more staffing and reduced airport capacities. I've never seen simultaneous PAR approaches discussed, let alone multiple going on at once. Compare with airports running simultaneous parallel ILS approaches, often being managed by one or two controllers. Multiple PARs would require one controller per airplane landing.

Oh yeah I agree, as you were talking a lot about installing costs I assumed that list would be a lost of installing costs... But in running costs, of course the PAR is highly expensive just because of the staff, totally agree! I have heard a PAR approache being flown once on the radio, that poor guy had an receiver failure and couldn't get down in the ILS. I believe that is about the only time they really do PAR approaches -  emergency...

I'll update my answer to make it obvious that I'm talking cost over time. I don't think the install + mx on an ILS for, say, 20 years would exceed the cost of constant PAR approaches for 20 years, but obviously that's conjecture.

@Maverick283 My impression just from reading around ASE was that PAR  /was/ a contingency protocol for emergency or exceptional situations.

If anyone is interested in GBAS in the US, you can read about it on the FAA site. https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/laas/

@Maverick283: A military-only example, but aircraft carriers use PAR routinely (an ILS could be used for guidance by an incoming enemy missile; PAR doesn't suffer from this weakness).


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In a non-symmetric turn, how do the side slip angle and thrust side slip angle affect the equations of motion?
I'm doing a problem on Flight Mechanics in which a banked turn is performed. The center of gravity of the aircraft is always within an horizontal plane.
In order to write the dynamic equations, I have to assume some simplifications and conditions. One of them is the following:

The thrust’s sideslip angle is equal and with opposite sign than the aeroplane’s sideslip angle, that is:
  ($\nu = −\beta$).
Side slip angle ($\beta$) is defined as the angle made by the velocity
  vector to longitudinal axis of the vehicle at the center of gravity in
  an instantaneous frame.
Thrust side slip angle ($\nu$) is defined as the angle made by the
  thrust vector to longitudinal axis of the vehicle at the center of
  gravity in an instantaneous frame.
  https://en.wikipedia.org/wiki/Slip_(aerodynamics)#Sideslip_angle

Then, I have to write the dynamic equations for the symmetric flight and for the non-symmetric flight.
My questions are:

In my opinion, the condition written above should not be accounted for the symmetric flight, so $(\beta = \nu = 0)$. Is this affirmation correct?
For the non-symmetric case, I have drawn the following scheme of velocity and thrust. But I'm not sure if it's correct because it doesn't make sense, despite that is what the condition says: $(\nu=-\beta)$. Is the scheme correct according to the condition? (The scheme is the top view of the aircraft.)

In your graphic, what do subscripts b and I mean? Usually b is body and I is inertial. But then why shouldn't thrust be parallel to the body x-axis?

Yes! It means that. The reason why thrust is not parallel to the axis is because the statement says that the thrust has a sideslip angle $\nu$ and I think this angle is measured between thrust and X-axis. Please correct me if I'm wrong. @DeltaLima

If I understand the situation correctly, the aircraft is flying with the body axis aligned with the inertial axis and slipping to the right. E.g. the aircraft is on close final, aligned with the runway and correcting for a crosswind from the right.

Can you state the definition of thrust's sideslip angle and airplane's sideslip angle? Between which two vectors/axis each is measured?

@JanHudec Yes! I just edited my post with these definitions.

@Airman01, the diagram appears to be correct according to that definition, but with engines fixed to the airframe I have to wonder what could cause the change of thus defined $\nu$.

Is this problem specifically addressing a propeller driven aircraft?

@DeltaLima the problem approach should not be addressed to any kind of aircraft. It's more like a physics problem, actually the plane can be considered as a point (center of gravity) that is performing a banked turn in such a way that the trajectory is a circumference in the horizontal plane.

The reason I am asking is that propellers have a tendency to produce a side force opposite to the sideslip angle which would explain the strange "simplification". Are you sure that  $\nu$ denotes the thrust side slip angle and that you are not confusing $v$ which usually denotes the component of relative wind velocity along the $Y_b$ axis?

@DeltaLima: On propellers the thrust force is offset in a direction orthogonal to the sideslip angle, i.e. up or down. I do not know any mechanism which would cause a 180° offset. Not in propellers, jets or rockets. Well, rockets with a faulty gimbal control could do this, but it would not take long until they crash.

Relying on physics, causing a mass to execute a circular path requires a suitable centripetal force. In an airplane in a banked balanced turn, this comes from the inward component of lift due to the bank angle.
However, if the turn is not properly co-ordinated, there can be additional contributions to the centripetal force from the power plant thrust no longer being directed tangentially and sidethrust on the airframe due to slip.
The extreme case is the flat turn where the wings remain level and the power plant thrust has an inward component due to the sideslip.
That said, apart from an airplane having vectoring thrust, the only reason for a thrust sideslip angle I can think of is that many single airscrew airplanes have built-in sidethrust to counteract engine torque. However there is no requirement for the engine sidethrust angle to equal the slip angle, so in that case the assumption that the two angles are the same cannot be valid.
The thrust line of an airscrew doesn't change with slip. The slip causes asymmetric thrust on the blades which precesses gyroscopically so the airscrew creates a couple which tends to increase the slip angle.

Would a twin with an engine out & some bank into the operating engine (common assumption & technique to lower Vmca) produce the angles being discussed here?


text:
Where exactly can I find the FAA's UAS pilot training course (ALC-451)?
I'm trying to get my commercial drone operators certificate. I already have a private pilot certificate, so from the FAA website, all I need to do is complete the "Part 107 small Unmanned Aircraft Systems (sUAS) ALC-451" course on faasafety.gov, then file some paperwork. But I can't find the course. Is there a direct link to it?

The site is opening allright, though I'm not exactly sure how its related to aviation as defined in help center.

The home page is working ... I can't access the actual course page though.

https://www.faasafety.gov/search/default.aspx?keywords=Part+107+small+Unmanned+Aircraft+Systems+%28sUAS%29+ALC-451&submit=Search

Looks like its intermittently working. is this the correct course?

I used the site to get my drone cert on Monday and it was working fine for me (around 10am eastern) as was IACRA

Yes, that is working! Thank you. I also updated my question to better fit posting guidelines.

@Arel If the site is working, the question is redundant, isn't it? :)

I couldn't find the course, so I assume others can't find it either. This post should be helpful to those people.

Even when faasafety.gov is working without issue, the course can be difficult to find with the site's search feature. The Part 107 Small Unmanned Aircraft Systems (small UAS) course is presently available from this direct link: Part 107 Small UAS Course.
Note that you will have to be logged in to do the course. If you follow that link and are not logged in to faasafety.gov, log in and then go to that link again.
Note also that faasafety.gov currently seems to be experienceing occasional technical issues, either due to maintenance or traffic volume. The link may not work reliably at present.


text:
Do takeoffs and landings in a Pilatus PC-12 count for currency in a Piper Archer?
I just read this:

No person my act as PIC of an aircraft carrying passengers unless, within the preceding 90 days, he/she has made three takeoffs and landings as the sole manipulator of the controls in an aircraft of the same category, class, and type (if required)

Does this mean that you are legal to take passengers in an Archer if you have logged three takeoffs and landings in the past 90 days in a Pilatus PC-12?

Category: Yes, both are "airplanes" as opposed to rotorcraft or gliders.
Class: Yes, both are single engine land planes, as opposed to multi-engined or sea planes.
Type: Yes, neither aircraft requires a type rating (both are under 12,500 lb max takeoff weight, neither is powered by a turbojet)
So the Piper Archer and Pilatus PC-12 qualify as currency for each other per this regulation.


text:
How can I create a fly-over waypoint in the G1000?
How do I make the G1000 fly over a user waypoint rather than fly by it, therefore not sequencing to the next waypoint until the aircraft has overflown the current one?
I’ve tried ATK Offset but with a sharp turn to the next leg (>120 degrees) this still does not work.

The OBS function will let you manually fly over the waypoint, but using that technique isn't actually toggling the waypoint property. I don't know how to do that.

Have you looked at this video?

The video discusses the use of ATK Offset which only works in set circumstances (i.e. on ~>120degs). It also describes simply putting the autopilot into heading hold mode (i.e. ignore the gps which will still auto sequence to the next waypoint at the moment of turn anticaption). Unfortunately this does not appear to be a function that the G1000 is capable of.